- Hong Kong Carbon Reduction Campaign
- Global forest carbon research
- Securing water supply in China's heartland
- Taking direct action
- Saving the Freshwater Gharial in the Ganges
- Cleaning up the Ganges
- Untangling our understanding of lianas and climate change
- The Panama Canal Watershed Experiment
- Protecting the Ganges: Interschool Recycling Workshop
- Cooking on natural gas in the Yangtze
- Tackling illegal deforestation
- Johannesburg's Rea Vaya Bus Rapid Transit Project
- Baicheng wind farm project
Untangling our understanding of lianas and climate change
Lianas are a characteristic feature of tropical forests. Recently scientists have speculated that lianas are becoming more common in tropical forests, impacting on the growth of individual trees, on the health of forests, and on their ability to store carbon.
Climate challenge
Led by the Smithsonian, 27 scientists from different countries around the world set out to test the hypothesis that lianas become more common as habitats become drier. These scientists aim to develop predictive models that can help forecast the impact of environmental change.
Insight and action
The scientists looked at liana and weather statistics at 24 different sites across the tropics. Data spanning a range of rainfall and seasonality were collected in forest plots in Mexico, Costa Rica, Panama, French Guiana, Ecuador, Brazil, Peru, Bolivia, Cameroon, Democratic Republic of Congo, India, Malaysia and China.
In a separate study, researchers removed lianas from eight gaps caused by fallen trees in forests in central Panama and compared the growth of other plant species in these gaps with eight gaps where the lianas were allowed to grow naturally.
In a third study, researchers analyzed 12 separate studies completed in tropical, subtropical and temperate forests across the Americas, Africa and Europe. These studies evaluated long-term data to test both the pattern of increasing liana abundance and biomass.
Outcomes
The first study showed that lianas grow most successfully in drier tropical forests, and liana density increases significantly as rainfall decreases and dry seasons get longer. The results of this study were published in the scientific journal Biotropica in July 2009.
The second study found that removing lianas actually increased tree growth by 55%, germination of tree seedlings by 46%, and local species diversity by 65%. The results were published in May 2010 in the journal Ecology Letters.
In February 2011, Ecology Letters published the third study, showing that lianas are increasing in neotropical forests. The ramifications of this are enormous, given that lianas reduce tree growth and increase tree mortality - thus reducing forest-level carbon storage.
These studies have contributed signifi cantly to scientifi c understanding of the impact of liana density on tropical forests, this new data is helping scientists to understand the impact of climate and atmospheric change on the forests which play such a key role in storing the world's carbon.
The increase in lianas, which have much less wood than trees, compensates only partially for the amount of carbon lost in the displaced trees. Because tropical forests contribute approximately a third of global terrestrial carbon stocks and net primary productivity, the effect of increasing lianas for tropical forest carbon cycles may have serious repercussions at the global scale.
Stefan Schnitzer, Smithsonian Research Associate
The HSBC Climate Partnership is a fi ve-year environmental programme between HSBC, the Climate Group, Earthwatch, the Smithsonian Tropical Research Institute and WWF. It aims to reduce the impact of climate change on people, forests, freshwater and cities, and accelerate the adoption of low-carbon policies.
